#include <bits/stdc++.h>

using namespace std;

const int oo = 0x3f3f3f3f;
const double eps = 1e-9;
const double PI = 2.0 * acos(0.0);


typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<string> vs;

#define sz(c) int((c).size())
#define all(c) (c).begin(), (c).end()
#define FOR(i,a,b) for (int i = (a); i < (b); i++)
#define FORS(i,a,b,s) for (int i = (a); i < (b); i=i+(s))
#define FORD(i,a,b) for (int i = int(b)-1; i >= (a); i--)
#define FORIT(i,c) for (__typeof__((c).begin()) i = (c).begin(); i != (c).end(); i++)


int s[3000];
int ep[3000];
int eu[3000];
int st[3000];

vector<pii> exSt;

int dp[3000][3000];

int main(){
	int n; cin >> n;
	
	map<double,int> events;

	FOR(i,0,n){
		cin >> s[i] >> ep[i] >> eu[i] >> st[i];
		events[s[i]] = i;
	}

	int np = 0;
	
	// by default all exams are non-pass
	vector<bool> passed(n, false);
	vector<bool> impossible(n, false);

	int lastTaken = -1;
	FOR(i,0,2*n){
		int lastTime = 0;
		int accumulated = 0;
		int cheapPass = 1000000;
		int cheapPassIdx = -1;
		int startToStudy = -1;
		bool aborted = false;
		for (auto [time, exam] : events){
			int timeToStudy = time - lastTime + accumulated;
			if (passed[exam]){
				if (timeToStudy < st[exam]){
					impossible[lastTaken] = true;
					passed[lastTaken] = false;
					aborted = true;
					break;
				}
				accumulated = timeToStudy - st[exam];
				lastTime = ep[exam];
			} else {
				if (!impossible[exam] && timeToStudy >= st[exam]){
					if (cheapPass > st[exam]){
						cheapPass = st[exam];
						cheapPassIdx = exam;
						
					}
				}

				// simulate further pretending we do not pass
				accumulated += time-lastTime;
				lastTime = eu[exam];
			}
		}
		if (aborted){
			lastTaken = -1;
			np--;
			continue;
		}
		if (cheapPassIdx == -1) break;
		passed[cheapPassIdx] = true;
		lastTaken = cheapPassIdx;
		np++;
	}


	cout << np << endl;
}